Role of channel activation in cognitive enhancement mediated by alpha7 nicotinic acetylcholine receptorsBriggsCAauthorGronlienJHauthorCurzonPauthorTimmermannDBauthorWeenHauthorThorin-HageneKauthorKerrPauthorAndersonDJauthorMalyszJauthorDyhringTauthorOlsenGMauthorPetersDauthorBunnelleWHauthorGopalakrishnanMauthor2009EnglishBACKGROUND AND PURPOSE: Several agonists of the alpha7 nicotinic acetylcholine receptor (nAChR) have been developed for treatment of cognitive deficits. However, agonist efficacy in vivo is difficult to reconcile with rapid alpha7 nAChR desensitization in vitro; and furthermore, the correlation between in vitro receptor efficacy and in vivo behavioural efficacy is not well delineated. The possibility that agonists of this receptor actually function in vivo as inhibitors via desensitization has not been finally resolved. EXPERIMENTAL APPROACH: Two structurally related alpha7 nAChR agonists were characterized and used to assess the degree of efficacy required in a behavioural paradigm. KEY RESULTS: NS6784 activated human and rat alpha7 nAChR with EC(50)s of 0.72 and 0.88 microM, and apparent efficacies of 77 and 97% respectively. NS6740, in contrast, displayed little efficacy at alpha7 nAChR (<2% in oocytes, < or =8% in GH4C1 cells), although its agonist-like properties were revealed by adding a positive allosteric modulator of alpha7 nAChRs or using the slowly desensitizing alpha7V274T receptor. In mouse inhibitory avoidance (IA) memory retention, NS6784 enhanced performance as did the 60% partial agonist A-582941. In contrast, NS6740 did not enhance performance, but blocked effects of A-582941. CONCLUSIONS AND IMPLICATIONS: Collectively, these findings suggest that a degree of alpha7 nAChR agonist efficacy is required for behavioural effects in the IA paradigm, and that such behavioural efficacy is not due to alpha7 nAChR desensitization. Also, a partial agonist of very low efficacy for this receptor could be used as an inhibitor, in the absence of alpha7 nAChR antagonists with favourable CNS penetration.Allosteric RegulationAnimalsAvoidance Learning/drug effectsAzabicyclo Compounds/administration & dosage/*pharmacologyBehaviorAnimal/drug effectsCell LineCognition Disorders/drug therapy/physiopathologyDose-Response RelationshipDrugFurans/administration & dosage/*pharmacologyHumansMaleMiceNicotinic Agonists/*pharmacologyOocytes/drug effects/metabolismOxadiazoles/administration & dosage/*pharmacologyPyridazines/pharmacologyPyrroles/pharmacologyRatsReceptorsNicotinic/*drug effects/metabolismXenopus laevisalpha7 Nicotinic Acetylcholine ReceptorPMID:19845675; PMCID:PMC2795215exported from refbase (http://www.strategian.com/refbase/refbase/show.php?record=1881), last updated on Tue, 11 Jul 2017 15:20:51 +0000texthttp://onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2009.00426.x/fullhttps://scholar.google.com/scholar?cites=12130738354452974975&as_sdt=1000005&sciodt=0,16&hl=enhttp://onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2009.00426.x/full19845675Briggs_etal2009British Journal of PharmacologyBr J Pharmacol2009continuingperiodicalacademic journal1586148614940007-1188